Electric cooker



Nov. 25, 1941. P, J, McCULLOUGH 2,264,094

ELECTRIC COOKER Filed Jan. 15, 1940 2 Sheets-Sheet l INVENTOR: PAUL J. MCuLLduGH A 2 TORNEY g 1941- P. J. M cuLLouGH ELECTRIC cdoxER Filed Jan.15, 1940 2 Sheets-Sheet 2 Patented Nov. 25, 1941 UNITED STATES PATENTOFFICE ELECTRIC 000m Paul I.

McCullough, St. Louis, Mo., assignor to Joseph Pavelka, St. Louis, Mo.

Application January 15, 1940, Serial No. 313,857

7 Claims. (Cl. 219-19) The invention relates to electric cookers andmore particularly to electric grills for cooking sausages, steaks,sandwiches and the like, waiile Another object is to vary the.temperature of the cooking sheets by a thermostatic control.

Another object is to avoid arcing in an electric circuit switch actuatedby a thermostatic device.

Another object is to prevent a change in thesetting of the temperaturecontrol unless the heater circuit is open.

Another object is to facilitate the discharge of excess grease from thelower cooking. sheet.

Another object is to construct an electric cooker with the featuresreferred to above so simply that it will have a low first cost and willwithstand careless or unskilled handling without injury.

Other objects and advantages will be apparent to those skilled in theart from the following descriptions wherein reference is made to theaccompanying drawings in which like numerals designate like partsthroughout the several views.

In the drawings Figure 1 is a horizontal section through the cooker bodywith its cooking plate removed to clearly illustrate the controlmechanism.

Figure 2 is a complete vertical section taken on the line 2-4 of Figure1.

Figures 3 and 4 are complete vertical sections taken on the lines 3-4and 4-4 respectively I of Flsure 1.

Figure 5 is a rear elevation of the cooker.

Figure 6 is a detail of th'e'cover support.

Figure 7 is a side view showing the cooker body in a tilted position.

Figure 8 is a wiring diagram.

The cooker main housing I is hinged at Htoabaseisoastoswingfromthenonnal position indicated in Figure 2 to thetilted position indicated in Figure '1.- Such movement may be elected bya cam 4 (Figure 4) Journalled on the trout wall of the housing andoperated manually by a knob a (Figure 2). The cam engages a as orthermostat It and having its other end roller 6 journalled on base 3 andas the cam is rotated housing 2 swings to and from base 3.

A lower cooking .sheet I extends across the top of housing 2 and may beheated by an electric resistance element indicated at II. A spout i2projects rearwardly from lower cooking plate I and will drain anysurplus grease on the cooking plate to a separate receptacle providedtherefor at the rear of the cooker. It the surplus grease is too thickto drain readily or if the cooker happens tobe standing on a table orcounter which slopes forwardly instead of being level, then the operatormay tilt the cooker housing and top plate by rotating knob 5 to effectmore rapid drainage.

Flanges III project rearwardly from housing! and carry vertical rails Rextending parallel to the rear wall of housing 2. A cover member Cmounting the upper cooking sheet 8 is pivoted at X to legs 9 which haveelongated slots slidably receiving rails R, the ends E of which are bentto overlap legs 8. The user may grasp handles D to raise the cover andits legs bodily from the full line position shown in Figure 2 to thedottedline position, and in any vertical position of the legs the covermay be swung about its pivot X from the horizontal position shown infull a thermostat device comprising two bimetal' line position in Figure2 to the dotted line position. The tilting of legs 9 by the weight ofcover 0 will hold the cover in any vertical adjusted position. SpringsII are tensed between the housing wall and the lower ends-oi legs I tocontribute to the support of the cover and to prevent shock when thecover is lowered. Lugs L on legs en888e the cover to hold it inhorizontal or upright position as desired.

Heating elements It and I4 are connected in parallel as indicated in thewiring diagram oi Figure 8 and their circuit includes atilting mercuryswitch it which may be controlled by 24 (Figures3and5)inthe-housingrearwall,

andhasanoflsetarm llssecuredtoalever ll (Figure 1) pivoted at one end tothe free end flanged and underlying the free end of thermostat l'l.Crank I! has a depending arm llb arranged to engage a finger 2| onswitch l5 and pivotally mounting the switch at 22 to a bracket Battached to housing 2. Pivot 22 is sodisposed relative to the centerofgravity of the switch that the switch tends to tilt in ananticlockwise direction to the position shown in Figure 8 in which themercury closes the heat circuit.

when both thermostats are cool, they have no eflect upon the positioningof crankshaft [9, Na, lib, and the switch will remain in the circuitclosing position except for a manual control As the thermostats heat,.the'

described below. outer end of strip It and the corresponding end oflever ll move upwardly, and the outer end of strip ll moves downwardlyengaging the corresponding end of lever ll. These opposite movements ofthe ends of the lever turn the lever in an anticlockwise direction(Figure 4) and also turn the crank shaft, which is rigid therewith, sothat its depending arm llb tiltsswitch I! in a clockwise direction toopen the heater circuit.

Bracket B has a lug K which engages finger 2i to limit pivotal movementof switch I! in a clock 'm'ountsacam24 (Flgures3and5). Thiscam isdisposed adjacent to shaft is and rotation of the cam from the lowposition indicated in Figure 5 will move shaft II to the right in slot20. The inclination of the slot is such that if cam 24 is moved from itshigh position to its low position, crank I! will slide down the slot tothe full line position shown in Figure 5.

Elements 23, 23a, and 24 comprise an adjustment feature whereby theheating of the cooking plates may be controlled. Obviously, less rotarymovement of crank arm lib is required to tilt the switch from closed toopen position when the crank is pivoting about the right-hand end ofslot than when the crank is pivoting about the left-hand end of slot 20.Hence, maximum relative movement of the free ends of thermostats l8 andI1 is required in opening the heater circuit when cam 24 is in theposition shown in Figures 3 and 5. V

The circuit may be opened and closed manually by a crank shaft havingends 2| Journalled in the front and rear walls of the housing (Figure 1)and having an intermediate oiiset portion 244 posite uppermost position.This movement is effected through a knob 28b secured to the forward endof the crank shaft. A lever 21 has one end pivoted at 21a to the rearwall'of the housing and has its other end overlying the offset portionIsa of crankshaft ll. A spring 22 tends to pull lever 21 downwardly, asshown in Figure 3, in

which position its swinging end presses downwardly on the offset portionIla of crank shaft I I! to rotate the latter to the full line positionshown in Figure 5 to open the heater circuit.

nected to a power source. v

lamp 26 is arranged in housing 2 and connected and closing the circuitbut subject'to control by the thermostat device regulated by knob 23a.

A tension spring 30 has one end attached to shaft 26a and the other endattached to shaft 23.

5 The pull of the spring tends to hold crank shaft 26 in on or offposition with its forward crank in engagement with a stop 3i (Figure 9)on the housing front wall. The friction between the spring and squareshaft 23 tends to hold the latl0 ter and cam 24 in any adjustedposition.

It is desired that the adjustment of the thermostat control cannot. bechanged accidentally.

as by the brushing of the attendants clothing against knob 23a. Also, itis desired that the adlll iustment of the thermostat control cannot bechanged intentionally while the circuit-is closed, otherwise there mightbe a coincidental automatic operation of the crank shaft l9 andadjusting shaft 23 which might result in arcing between 90 the switchcontacts. To this end, shaft "is locked against rotation when crankshaft 26 and knob 230 are in circuit closing position. The lockcomprises a toothed wheel." (Figure 4) secured to shaft 23 and a lever22 pivoted at 22a to the :5 front wall of the housing and having one enddisposed to interengage with the teeth of wheel 33. When crank shaft 26is' in the position shown in Figures 3 and 4 in which it permits theswitch to close and to be controlled by thermostats If 30 and i1, lever32 assumes the full line position,

shown in Figure 4 with its left-hand end spacedv from wheel 33. Whencrank shaft 26 is turned 180 degrees to the circuit opening.position,its offset portion 26a will lift lever 32 to the dotted 85 line positionshown in Figure 4, and the forward end of the lever will engage wheel 33to hold the same against rotation.

An electric plug 31 is provided on housing 2 whereby heating elements l3and I4 may be con- Also, an indicator in parallel with heating elementsit and i4 and in series with switch l5, as shown in Figure 8, I toindicate flow of current through the heating circuit. Obviously, lamp 36will be illuminated when switch i5 is in closed circuit position and thelamp will be unlighted when switch i5 is in open circuit position.

The electric cooker described above operates as to follows:

To heat cooking sheets I and 8, knob 28b is moved manually to closedcircuit position whereby crank oflset 26a moves lever 21 out ofengagement with crank oflset "a (Fig. 3),,thus

permitting switch I! to pivot under-the influence of gravity to closedcircuit position. As cooking sheets I and 8 become heated, lever I8 andcrank shaft I! are pivoted by strips l8 and I1 and, when the cookingsheets attain a desired temco perature as determined by the thermostatconing sheets I and 8.

As lower cooking sheets I cools again, crank shaft l9 and lever l8 pivotin the reverse direction to release switch Ii and to allow the switch tomove to closed circuit position under the in- Whencrank shaft 22 isrotated 180 de ees by fluence of gravity, in which position the switchknob 26b, its offset portion-2M lifts lever 21 against the pull ofspring 28 and frees crank shaft II from the lever, permitting the heavyend of switch I to swing crank shaft arm llb remains until the desiredtemperature of the cooking sheets is attained again.

Cooking sheets I and I may be maintained at any temperature desired bychanging the setting to the lef f m h pofltion shown in u e 5 16 ofthermostat control knob 23a to rotate cam 24 escapes which moves crankshaft it in slot 2 and shifts the position of depending arm l9b relativeto switch l5.

When the manually controlled switch knob 26b is in ,closed circuitposition, lever 32 engages wheel 33 on shaft 23 and prevents movement ofknob 25?) and change the setting of the thermostat control.

The movement of thermostats i6 and ll in opposite directions producesmore rapid rotation of lever 18 than would be effected if the lever hadonly a single actuating thermostat. The rotation of the lever is furtheraccelerated by the fact that as thermostat it approaches the lowerheating sheet, it is subjected to a gradually increasing temperature andtherefore moves more rapidly and tends to open the circuit more promptlyupon the attainment cl 9. predetermined critical temperature in thesheet. Similarly, after the circuit is opened and cold batter is pouredonto the sheet, the temperature of the cooking plate is lowered and thereturn movement of thermostat i1 will be accelerated as the thermostatapproaches and contacts with the plate. Hence, the closing of thecircuit will be accelerated as the temperature dropssubstantially belowthe predetermined critical point. This action would be particularlynoticeable and advantageous in a waiile iron following the removal oi acooked waiile.

From the above description, it will be apparent that the cooking sheetsof an electric cooker utilizing an electrical control system constructedaccording to this invention, will be maintained efiectively at apredetermined temperature. Also, after the thermostat control isregulated so that the cooking sheets are maintained at a desiredtemperature, the setting of the thermostat control cannot be changedaccidentally by the operators brushing against the control knob. Inaddition, the cooking sheet of a cooker of the lclnd described hereinmay be freed of excess grease and other liquid substances quickly andeasily. Also, the cooker is cheap to manufacture, simple in design andeffective in operation.

While only one embodiment of this invention has been shown anddescribed, it should be understood that other forms and arrangements maybe used without departing from the scope of this invention asdeflned inthe appended claims. For instance, an electrical control systemasdescribed herein may be used otherwise than on electric cookers, andthe control system may be utilized whenever temperature regulation isdesired.

I claim:

1. In an electrical heating device, a housing, a switch member pivotallymounted on said housing to open and close the electric circuit, a crankshaft resting on an elongated bearing inclined so that the relationbetween said, shaft and switch pivot varies as said shaft moves alonsaidbearingsaidshafthavlnganarminoperative connection with said switchmember, a manually adjustable cam for positioning saidshaftalongsaidbearingtovarythethrowof arm relative to said switch, and athermostatic device to actuate said shaft.

2. In an electrical heating device, a housing, a switch member pivotallymounted on said housing to open and close the electric circuit, a crankshaft resting on an elongated bearing inclined so that the relationbetween said shaft andswitchpivotvariesassaidshaftmovesalong saidbearing, said shaft having an arm at one end in operative connectionwith said switch member, a manually adjustable cam for positioning saidshaft along said bearing to vary the throw of said arm relative to saidswitch, a lever fixed to said shaft at a point spaced from said arm, apair of bimetallic strips anchored to said housing with the free ends ofsaid strips fluid contact switch connected electrically in series withsaid heater element to tilt free of resistance, other than its inertia,in opposite directions into circuit opening and circuit closingpositions, a pair of bimetallic thermostatic strips disposedsubstantially parallel to each other and extending from end to andalongside of said sheet withan adjacent pair or their and pore tions infixed relation to said sheet, one strip having its high expansionelement opposing said sheet and the other strip having its low expansionelement opposing said sheet so that said strips distort in oppositedirections when subjected to a change in temperature, and an operativeconnection between said switch and the other unflxed end portions ofsaid strips whereby the opposite movements of the lattertioned endportions tilt the switch from one of its said positions to the otherwhen the strips are subject to temperature changes.

4. A device as described in claim 3 in which the connection between theswitch and the thermostatic strips includes a shaft having a crankconnection to the uniixed end portions of both of said strips, wherebythe shaft is rotated as said strips move in opposite directions.

5. In a cooker, a cooking sheet, an electric resistance element forheating said sheet, a circuit including a switch for said element, apair of elongated thermostatic strips with anchored ends and withmovable ends operatingly connected to said switch to move it from oneposition to another, said strips being adapted to bend in oppositedirections when heated and to bend in opposite directions when cooledand being disposed throughout their length alongside of said cookingsheet whereby as said cooking sheet approaches a critical temperatureone strip moves towards said sheet to be in substantial contacttherewith from end to end of the strip and the other strip moves awayfrom said sheet.

6. In an electric control system, a fluid contact switch mounted to tiltfreely from a. circuit closing to a circuit opening position, a pair ofbimetallic strips having respective portions arranged to move inopposite directions when subiectcd to a change in temperature, a barextending transversely of said portions with its ends disposed forengagement by said portions, a shaft extending transversely of said barand fixed thereto and being freely rotatable about its axis by theopposite movement of the ends of said bar by said portions, said shafthaving a crank armarranged to tilt said switch into one of saidpositions when said bar is shifted in one direction by said strips, saidswitch being arranged to return by gravity to its other position whenreleased from said crank arm by the reverse movements of said strips. 7.In a cooker of the type described, a substantially horizontal cookingplate, thermostatic a fluid switch adjacent said member, a shaftexi 10tending transversely of said member and pivoted to rotate freely thereonand having a crank arm operativeiy connected to said switch to tilt thelatter about a pivot and having a'lever extending transversely of and inopposite directions from the shaftaxis, the ends of said lever beingconnected respectively to the thermostat portions whereby the crank isrotated by the movement of said thermostat portions in oppositedirections to operate said switch tree of any resistance by said shaftand said switch ertia. 1

PAUL J. MCCUIJOUGH;

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